The invention relates to an apparatus having an electroacoustic transducer, and further relates to an electroacoustic transducer.
Such an apparatus, which takes the form of a mobile telephone, and such an electroacoustic transducer are known from, for example the patent document U.S. Pat. No. 5,903,076 A. In the solution known from said patent document the moving coil of the electroacoustic transducer, which moving coil is arranged to receive sound signals for the generation of acoustic sound waves with the aid of the transducer""s diaphragm, which is attached to the moving coil, is also used for the generation of perceptible vibrations. In order to generate such perceptible vibrations the moving coil of the transducer, which is disposed in the useful magnetic field of the magnet system, is arranged to receive an a.c. signal of comparatively low frequency, which causes the moving coil, which is disposed in the useful magnetic field of the magnet system, to produce vibrations of such a high amplitude that a part of the diaphragm which is attached to the moving coil and which serves as a vibration generating part, strikes against a stationary vibration generating part in cyclic succession, which cyclically recurrent striking of the vibration generating part of the diaphragm against the stationary vibration generating part leads to the desired generation of perceptible vibrations, which are readily perceptible by a user. The known solution has the problem that in the electroacoustic transducer, in order to achieve a high-quality generation of sound signals the moving masses, i.e. the masses of the moving coil and the transducer parts connected to the moving coil, should be minimal, on the one hand, and in order to achieve a maximal vibratory effect, the moving masses, i.e. the moving masses of the moving coil and the transducer parts connected to the moving coil, should be maximal, on the other hand. This means that contradictory requirements apply, which can only be solved by a compromise but this requires trade-offs both in view of a sound signal generation of the highest possible quality and in view of a maximal vibratory effect and it is therefore not possible to achieve an optimum result for neither of the goals. Furthermore, with the known solution the moving coil and the diaphragm are subjected to comparatively high mechanical loads, which is unfavorable in view of a minimal wear and a long lifetime.
It is an object of the invention to preclude the afore-mentioned problems and to provide an improved apparatus and an improved electroacoustic transducer and to achieve both an optimum sound signal reproduction and an optimum vibratory effect with the simplest possible means and without the moving coil and the diaphragm being subjected to excessive mechanical loads.
According to the invention, in order to achieve the afore-mentioned object, an apparatus having an electroacoustic transducer is provided, which transducer has a magnet system which generates a useful magnetic field in a useful field area and which generates a stray magnetic field in a stray field area, and which magnet system is used to realize vibration generating means for the generation of vibrations which are perceptible by a user of the apparatus, wherein the vibration generating means include, in addition to the magnet system of the transducer, at least one movably mounted vibration generating coil arranged in the area of the stray field generated by means of the magnet system of the transducer.
Furthermore, according to the invention, in order to achieve the afore-mentioned object, an electroacoustic transducer is provided, which has a magnet system which generates a useful magnetic field in a useful field area and which generates a stray magnetic field in a stray field area, and which magnet system is used to realize vibration generating means for the generation of vibrations which are perceptible by a user of the apparatus, wherein the vibration generating means include, in addition to the magnet system of the transducer, at least one movably mounted vibration generating coil arranged in the area of the stray field generated by means of the magnet system of the transducer.
As a result of the provision of the characteristic features in accordance with the invention it is achieved by means of a very simple construction that an optimum sound signal generation is guaranteed using the magnet system of the electroacoustic transducer and with the aid of the moving coil included in this transducer and disposed in the useful field area and that an optimum vibratory effect is guaranteed with the aid of the at least one vibration generating coil disposed in the stray field area, which is particularly so because the masses of the moving coil and the parts connected to the moving coil and the masses of the at least one vibration generating coil and any parts connected to the at least one vibration generating coil can be selected independently of one another and can therefore each be dimensioned for an optimum result. Moreover, excessive mechanical loading of the moving coil is thus avoided.
In an apparatus in accordance with the invention and in an electroacoustic transducer in accordance with the invention the desired result can be achieved with only one vibration generating coil. However, it has proved to be very advantageous when, in addition, the vibration generating means include two movably mounted vibration generating coils arranged in the stray field area, and the two vibration generating coils are arranged in series opposition or in anti-parallel characteristic. In this way, it is achieved that the stray magnetic field of the magnet system, which field is oppositely poled at the two magnet ends (north pole and south pole), is utilized better and, as a result of this, a better vibratory effect is achieved.
In an apparatus in accordance with the invention and an electroacoustic transducer in accordance with the invention it has proved to be particularly advantageous when, in addition, the vibration generating means include, in addition to the at least one vibration generating coil, a metal part which is mechanically connected to the at least one vibration generating coil and which consists of a soft-magnetic material, and when the magnet system is basically ring-shaped, and the magnet system generates the stray magnetic field, which emanates from its outer peripheral area, and the at least one vibration generating coil is annular and is arranged to be coaxial with the axis of the magnet system and is mounted so as to be movable parallel to the axis of the magnet system. In this way, it is achieved that with the aid of the metal part of a soft magnetic material the stray magnetic field is enhanced as regards its direction and magnitude in the area in which the at least one vibration generating coil is disposed and, as a consequence, an improved vibratory effect is obtained. Furthermore, this solution has the advantage that the masses moved by means of the at least one vibration generating coil is increased substantially by the mass of the metal part, which is also advantageous for an optimum vibratory effect.
In an apparatus in accordance with the invention it has further proved to be advantageous when, in addition, an a.c. generator has been provided, which generator is adapted to generate an a.c. signal having a frequency of, preferably, between 50 Hz and 200 Hz, and the a.c. generator is connected to the at least one vibration generating coil in an electrically conductive manner and supplies the a.c. signal generated by it to the at least one vibration generating coil. This provides an embodiment having a vibration generating coil of a maximal diameter, which is advantageous in view of a simple construction and in view of an optimum vibratory effect.
The above-mentioned as well as further aspects of the invention will become apparent from the embodiments described hereinafter by way of example and will be elucidated with reference to these examples.